Never before has the imbalance between the American and National Leagues regarding Rule 6.10 been more of a potential problem.

The designated hitter rule has been controversial from day one. It’s been criticized and even confusing since it was born. So it’s only natural that Major League Baseball’s once-bold experiment will continue to exist unevenly and indefinitely.

The DH debate won’t die.

“A little controversy between the leagues is really not all bad,” Commissioner Bud Selig said before the All-Star game in New York on Tuesday.

Selig cast one of the votes for using the designated hitter in AL games starting in 1973, when he owned the Milwaukee Brewers, then an AL franchise. He acknowledged this week that further geographic changes to divisions could force MLB to either scrap the DH altogether or install it for the NL, but that’s a future possibility and not an imminent plan.

When Houston switched to the AL West this year to even out the leagues at 15 teams each, daily interleague games became a necessity of the schedule.

“At the moment,” Selig said, “we are not going to change it.”

Perhaps the most polarizing of this sport’s many quirks and imperfections, the designated hitter came to be when AL teams sought to boost their then-lagging product. The decision was made during a time when the two leagues were far less integrated than now.

The gimmick not only worked to increase scoring and attendance but created a way for some of the game’s greatest hitters to extend their careers — and make a lot more money.

Orlando Cepeda even credited the rule for boosting his Hall of Fame credentials, after Boston signed him for the 1973 season following a long career with San Francisco.

“That was one of the best years, because I was playing on one leg and I hit .289,” Cepeda said earlier this season. “And I hit four doubles in one game. Both my knees were hurting, and I was designated hitter of the year.”

Designated hitters last year had the second-highest average salary by position at $8.1 million, behind first basemen at $8.6 million. That’s the main reason why eliminating the DH to bring the AL back on line with the NL is almost unfathomable. Boston’s David Ortiz, who recently passed Harold Baines on the career list for hits by a DH, is making $14 million this season at age 37.

The designated hitter has also helped teams keep their best players in the lineup while giving them some type of rest. Minnesota All-Star catcher Joe Mauer is a prime example. When he needs a break from crouching behind the plate, manager Ron Gardenhire can keep his potent bat in the lineup at DH.

“I get a lot of questions about the DH, how we use it and all that stuff, but basically the way I see it is I’d rather see David Ortiz hit than some pitcher,” Mauer said, intending no offense to his own teammates. “So we’ll see. It is what it is right now.”

Most of Mauer’s AL peers predictably express support for the DH’s existence, even if a lot of them would rather play a position than sit around between at-bats. The power of the players’ union, protective of this lucrative and prominent job, is another undeniable force for the DH. And despite the complaints from dads with sleepy kids at long games, fans usually enjoy seeing runs cross the plate.

The cumulative AL batting average has beaten the NL’s mark in each of the first 40 seasons of the DH. The last time the NL hit above .270 was 1939. The AL has 11 seasons of .270-plus batting during the DH era.

There are purists who have a hard time forgiving MLB for the installing the DH, though. Remember the movie Bull Durham, when Kevin Costner’s character, Crash Davis, launches his crude rant about the qualities and superficialities of life?

“I believe there ought to be a constitutional amendment outlawing AstroTurf and the designated hitter,” he said.

The NL guys, naturally, tout the purity of the no-DH game and the additional substitution strategy it provides. Many pitchers simply find it fun to try to hit — even if it means sometimes looking silly swinging meekly at strike three.

Yes, DH conflicts keep on coming — even in spring training. The home team is supposed to decide whether or not to use it and sometimes managers disagree.

Cincinnati’s Dusty Baker wanted to use Shin-Soo Choo in that role for an exhibition game in March as a precaution for his tight right quadriceps, but Arizona’s Kirk Gibson insisted on keeping the pitcher in the lineup so he could let starter Brandon McCarthy take some swings. Baker and Gibson argued before the game about it at home plate. Gibson prevailed because the Diamondbacks were the host team.

When the games count, of course, the DH is used in AL ballparks and pitchers bat in NL venues.

This year, that will force Detroit manager Jim Leyland to leave designated hitter Victor Martinez out of the lineup at Miami on the final weekend of the regular season while the other teams in the league use their DH as usual. If the AL Central or wild-card races are still unsettled then, that’s the kind of potentially pennant-altering wrinkle that could someday prompt a change.

“I think that we need to get a unified set of rules, and I believe that we will get there some day,” the 68-year-old Leyland said. “I don’t know if I will be there to see it, but I think we will get there. I don’t care which way we go, but I think that without question we need to do it.”